International Journal of Advanced and Applied Sciences, 6(7) 2019, Pages: 77-82

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The effect of normal treatment methods at home in the removal of heavy metals from surface of rice distributed in Riyadh region

Hanan F. A. AL-Harbi *, Mashael Makki Mohammed Aljaish, Nora Hamad Saad Aljhfl Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia

A R T I C L E I N F O A B S T R A C T

Article history: Received 10 February 2019 Received in revised form 9 May 2019 Accepted 15 May 2019

Cleaning of rice with water with or without prior soaking may decrease the levels of heavy metals. The current study evaluated the efficacy of ordinary treatment techniques such as water washing in expelling the heavy metals found on the rice grains. Three varieties of rice were chosen: Abu Kass and Al Walimah from Riyadh area. Assessments were performed by Scanning Electron Microscopy (SEM). The two most common treatment techniques were washing a few times or after soaking for two hours. Diverse rates of heavy metals were present on the surface of rice grains of various types. A total of 15 different types of metals were found on the surface of samples with Zn, Cu, and Pb being present in all varieties of rice. Washing several times and soaking for two hours was effective in removing heavy metals from rice. However, important elements like Zn (15.9%), Mg (23.82%), K (22.05%) and Ca (16.75%) were lost to water after washing for several times. Interestingly, the concentrations of Hg and Pb were found to be high in Abu Kass rice (Hg: 19.7%; Pb: 13.4%); this can raise serious health concerns warranting further investigations. The presence of Pt in Abu Kass rice without washing (54.5%) and after washing several times (73.7%) is also a cause of concern. The results demonstrated the effectiveness of washing for several times and soaking for two hours to help in total dilution or removal of the elements. Soaking followed by washing may be more effective in removing more elements.

Keywords: Heavy metals Rice Scanning electron microscope Soaking Washing

© 2019 The Authors. Published by IASE. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction

*Rice (Oryza sativa) is one of the most important food types in the world. It is considered an essential and almost daily meal in many countries. Rice plays an integral part of the staple diet and, any contamination with xenobiotics raises serious health concerns. More recently, possible contamination of rice with heavy metals arising from numerous sources indicates one of the disadvantages of rapid industrialization. Amongst potential xenobiotic contaminants, heavy metal pollution has always been a major cause of concern (Duffus, 2003). Heavy metals such as Cd, Pb, Hg can accumulate on rice through air, water and food. Health implications of unwanted heavy metal exposure can cause toxicity wherein serious and fatal effects can be manifested if they are obtained in large quantities and exceed the

* Corresponding Author. Email Address: hhanan@ksu.edu.sa (H. F. A. AL-Harbi)

https://doi.org/10.21833/ijaas.2019.07.010 Corresponding author's ORCID profile:

https://orcid.org/0000-0002-4653-8717 2313-626X/© 2019 The Authors. Published by IASE. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

maximum dose, especially in pregnant women, cancer patients, and young people (Qu et al., 2012). The presence of heavy metals in rice even at trace levels needs to be given special attention owing to the potential health implications (Al-Saleh and Abduljabbar, 2017; Loutfy et al., 2006).

The release and accumulation of heavy metals due to rapid industrialization and the inability of heavy metals to undergo biological degradation causes their deposition in healthy tissues. Heavy metals, for example, Cd, Cr, Ni, and Hg, from mining, and wastewater discharge are regular contaminants of arable soil (Duffus, 2003; Qu et al., 2012; Pehlivan et al., 2009). These lethal substantial metals can be ingested and amassed by plants and in the long run enter the human body through sustenance admission. Sustenance utilization is the real introduction pathway, and presentation hazard from ingestion surpasses dangers from inward breath and dermal contact (Loutfy et al., 2006). A recent review (Jaishankar et al., 2014), indicated that most of the food pollution was due to heavy metals, amongst which, lead and cadmium were shown to be the most toxic. It is important to note that rice of obtained from certain countries were observed to have a

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record of contamination in the fields (Al-Saleh and Abduljabbar, 2017; Zhao et al., 2015).

Many plant species have varying capacities to either remove or accumulate heavy metals; therefore, there are reports indicating that certain species may accumulate specific heavy metals, causing a serious risk to human health when plant-based foodstuffs are consumed (Fytianos et al., 2001). Substantial levels of heavy metals were found in sheltered rice obtained from China (Zhao et al., 2015). This indicates that the treatment processes employed for the removal of heavy metals plays a major role in diluting their concentrations. The usual process of cleaning of rice either without or with prior soaking has not been previously investigated to decrease the levels of heavy metals. The aim of this research was to therefore to investigate the effectiveness of the methods used in our homes to wash rice in removing the heavy metals from rice.

2. Methods

Collection of rice samples was performed in the Riyadh region of Saudi Arabia. All rice samples were obtained within the production time period of 2015-

2016. Based on the results of the survey, 44% use Abu Kass rice and 38% use Al Walimah rice. The rice varieties were produced in India. Each sample of rice was divided into three groups:

Group I: Left without washing, Group II: Washed several times, Group III: Rice soaked for two hours

Rice samples were air-dried in the laboratory for

several days at room temperature, and examined using a scanning electron microscope (G.E.O.L 76105 field emission SEM) to estimate the levels, type and percentages of various heavy metals on the surface of the samples (Espinosa-Mendoza et al., 2012; Batista et al., 2018; Echlin, 2011; Goldstein et al., 2007).

3. Results

Heavy Metal Concentrations on the surface of rice surface by weight (%): Heavy metal concentrations on the surface of rice samples along with SEM images are shown in Table 1 and Figs. 1-3.

Table 1: Heavy metals found in Al Walimah and Abu Kass rice

Abu Kass Al Walimah Soaked or two

hours Washed several

times Without washing

Soaked for two hours

Washed several times

Without washing

39.45% 6.0% 3.3% 18.94% 17.8% Zn - - - 37.86% 11.00% 17.0% Mg

1.17% - 0.2% 3.26% - - Al - - - 7.83% 16.19% 6.0% P - - - 13.67% 24.54% 28.6% K - - - 12.61% - - Ca - - 0.1% - - - Ti

66.47% 7.0% 4.6% 17.34% 15.49% 30.3% Cu - - 1.9% - - - As

1.59% - 2.4% - - - Cd - - - - - - Au - - 19.7% - - - Hg

2.76% - 13.4% 3.27% - - Pb - 13.3% - - 32.79% - S - 73.7% 54.5% - - - Pt

The results showed that 15 types of metals were found at different rates on the surface of the investigated samples (Zn, Mg, Al, P, K, Ca, Ti, Cu, As, Cd, Au, Hg, Pb, S and Pt). Zn, Cu and Pb were present in all varieties of rice. Washing the rice for several times and prior soaking of rice for two hours was substantially effective in removing heavy metals. However, there was a loss in important elements like Zn (15.9%), Mg (23.82%), K (22.05%) and Ca (16.75%) after washing rice for several times. Moreover, the concentrations of Hg and Pb were found to be high in Abu Kass rice (Hg: 19.7%; Pb: 13.4%). Pt was found in Abu Kass rice without washing (54.5%) and after washing several times (73.7%).

Effective the methods washing and soaking to remove the Heavy Metals from rice surface:

Washing rice samples for several times was less effective than the soaking process for two hours for removing heavy metals. Furthermore, in Al Waleema

rice, a reduction of elements Mg K Cu was observed (prior to washing: 17.06 %, 28.67%, 30.33%; post washing: 11.00%, 24.54%, 15.49%), respectively. This process also caused the appearance of some new elements on the surface (Table 1; Figs. 2 and 3).

Fig. 1: Scanning electron microscopy images of Al Walimah

and Abu Kass rice

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(a)

(b)

(c)

Fig. 2: Composition of heavy metals in Al Walimah rice (a) without washing, (b) after washing several times and (c) after soaking for two hours

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00%

Zn Mg Al P K Ca Ti Cu As Cd Au Hg Pb S Pt

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00%

Zn Mg Al P K Ca Ti Cu As Cd Au Hg Pb S Pt

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00%

40.00%

Zn Mg Al P K Ca Ti Cu As Cd Au Hg Pb S Pt

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(a)

(b)

(c)

Fig. 3: Composition of heavy metals in Abu Kass rice (a) without washing, (b) after washing several times and (c) after soaking for two hours

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

Zn Mg Al P K Ca Ti Cu As Cd Au Hg Pb S Pt

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Zn Mg Al P K Ca Ti Cu As Cd Au Hg Pb S Pt

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

Zn Mg Al P K Ca Ti Cu As Cd Au Hg Pb S Pt

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4. Discussion

In order to observe the potential health risk of pollutants in food, the route and level of exposure in target organisms needs to be estimated. While many possible pathways for xenobiotic exposure to humans exist, the food chain is the most important (Caussy et al., 2003). Owing to this, it is critical to make sure that xenobiotics such as heavy metals do not enter the food chain above a certain limit (Caussy et al., 2003; Balkhair and Ashraf, 2016).

The human hazard appraisal evaluation is of prime significance in nations, for example, Saudi Arabia, where the wastewater water system practice remains unregulated. Moreover, rice consumption has been distinguished as one of the significant sources of human exposure to poisonous heavy metals because of their aggregation in rice grains (Satpathy et al., 2014). The rice genotypes also additionally act as the main factors in influencing the transmission and bioavailability of heavy metals in the soil-rice system (Cheng et al., 2006; Zeng et al., 2008).

The current study was conducted to understand the effectiveness of routine washing procedures in removing heavy metals from the surface of three varieties of rice, viz., Abu Kass and Al Walimah. We showed that approximately 15 types of metals appeared at different rates on the surface of samples including some hazardous metals such as Hg, Pb, Cd Cu and Pt which can have potential adverse health implications on human health. Amongst all the heavy metals, we observed, Zn, Cu, Pb were found in all samples. Studies have reported that the levels of cadmium and lead in 50 different kinds of rice exceeded the contaminant limit. This could probably be related to the strong adsorption capacity for lead, which indicates the need to rethink about the currently designed control estimates (Wen-Juan et al., 2016). Cd and Pb are considered to be non-essential metals and causing many health risks, even at very low concentrations (Ikeda et al., 2000; Zhuang et al., 2009) and can cause physiological degradation such as mental retardation and impact vital functions (Mohanty et al., 2011). Interestingly, amongst the levels of basic micronutrients for plants, Cu and Zn were the most abundantly reported for wheat and rice (Asgary et al., 2017). However, the existence of Pt needs further evaluation because Pt is usually observed in many wild plant species (Vatansever et al., 2017). The use of reclaimed soils polluted with heavy metals for agricultural production may cause accumulation of Cd and Cu (Reith et al., 2014). Another point to be noted is the presence of Hg in small quantities in one sample. Since, Hg is a dangerous element even in small proportions and can act as cumulative poisons causing neurological and renal disturbances, additional studies are needed for further assessments (Li et al., 2012).

Washing of seeds after soaking and washing several times were effective in removing many heavy metals. This is the first study to investigate the

efficacy of the home washing methods to remove the heavy metals from the rice. Also, we have employed the use of the high resolution scanning electron microscope to support our findings.

5. Conclusion

In the current study, the effectiveness of the home washing methods in the total dilution or removal of the heavy metals was studied. The effectiveness of soaking followed by washing was found to be more effective in removing heavy metals. In addition, some of the heavy metals appeared at different rates on the surface of samples. Further studies are needed to understand the release of elements within the grain and the possible long term implications of the released heavy metals on human health especially when staple foods are contaminated.

Acknowledgement

This research project was supported by a grant from the “Research Center of the Female Scientific and Medical Colleges”, Deanship of Scientific Research, King Saud University, Riyadh, Kingdom of Saudi Arabia.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

References

Al-Saleh I and Abduljabbar M (2017). Heavy metals (lead, cadmium, methylmercury, arsenic) in commonly imported rice grains (Oryza sativa) sold in Saudi Arabia and their potential health risk. International Journal of Hygiene and Environmental Health, 220(7): 1168-1178. https://doi.org/10.1016/j.ijheh.2017.07.007 PMid:28780210

Asgary S, Movahedian A, Keshvari M, Taleghani M, Sahebkar A, and Sarrafzadegan N (2017). Serum levels of lead, mercury and cadmium in relation to coronary artery disease in the elderly: A cross-sectional study. Chemosphere, 180: 540-544. https://doi.org/10.1016/j.chemosphere.2017.03.069 PMid:28431391

Balkhair KS and Ashraf MA (2016). Field accumulation risks of heavy metals in soil and vegetable crop irrigated with sewage water in western region of Saudi Arabia. Saudi Journal of Biological Sciences, 23(1): S32-S44. https://doi.org/10.1016/j.sjbs.2015.09.023 PMid:26858563 PMCid:PMC4705247

Batista AH, Melo VF, Gilkes R, and Roberts M (2018). Identification of heavy metals in crystals of sand and silt fractions of soils by scanning electron microscopy (SEM EDS/WD-EPMA). Revista Brasileira de Ciência do Solo, 42: 1-16. https://doi.org/10.1590/18069657rbcs20170174

Caussy D, Gochfeld M, Gurzau E, Neagu C, and Ruedel H (2003). Lessons from case studies of metals: Investigating exposure, bioavailability, and risk. Ecotoxicology and Environmental Safety, 56(1): 45-51. https://doi.org/10.1016/S0147-6513(03)00049-6

AL-Harbi et al/International Journal of Advanced and Applied Sciences, 6(7) 2019, Pages: 77-82

82

Cheng DW, Guoping Z, and Haigen Y (2006). Genotypic and environmental variation and their stability of As, Cr, Cd, Ni and Pb concentrations in the grains of Japonica Rice. ACTA Agronomica Sinica, 32: 572–579.

Duffus JH (2003). "Heavy metals"-A meaningless term? (IUPAC Technical Report). Pure and Applied Chemistry, 75(9): 793-807. https://doi.org/10.1351/pac200375091357

Echlin P (2011). Handbook of sample preparation for scanning electron microscopy and X-ray microanalysis. Springer Science and Business Media, Berlin, Germany.

Espinosa-Mendoza RE, Solorza-Feria J, Arenas-Ocampo ML, Camacho-Díaz BH, Villar-Martínez D, Angélica A, and Jiménez-Aparicio AR (2012). Morphostructural characterization of rice grain (Oryza sativa L.) variety Morelos A-98 during filling stages. The Scientific World Journal, 2012: Article ID 940293. https://doi.org/10.1100/2012/940293 PMid:22645473 PMCid:PMC3356751

Fytianos K, Katsianis G, Triantafyllou, Zachariadis G (2001). Accumulation of heavy metals in vegetables grown in an industrial area in relation to soil. Bulletin of Environmental Contamination and Toxicology, 67(3): 423-430. https://doi.org/10.1007/s001280141 PMid:11479673

Goldstein JI, Newbury D, Joy D, Lyman P, Echlin E, Lifshin L, Samyer JM (2007). Scanning electron microscopy and X-Ray microanalysis. 3rd Edition, Plenum Press, New York, USA.

Ikeda M, Zhang ZW, Shimbo S, Watanabe T, Nakatsuka H, Moon CS, and Higashikawa K (2000). Urban population exposure to lead and cadmium in east and south-east Asia. Science of the Total Environment, 249(1-3): 373-384. https://doi.org/10.1016/S0048-9697(99)00527-6

Jaishankar M, Tseten T, Anbalagan N, Mathew BB, and Beeregowda KN (2014). Toxicity, mechanism and health effects of some heavy metals. Interdisciplinary Toxicology, 7(2): 60-72. https://doi.org/10.2478/intox-2014-0009 PMid:26109881 PMCid:PMC4427717

Li Q, Chen Y, Fu H, Cui Z, Shi L, Wang L, and Liu Z (2012). Health risk of heavy metals in food crops grown on reclaimed tidal flat soil in the Pearl River Estuary, China. Journal of Hazardous Materials, 227: 148-154. https://doi.org/10.1016/j.jhazmat.2012.05.023 PMid:22657103

Loutfy N, Fuerhacker M, Tundo P, Raccanelli S, El Dien AG, and Ahmed MT (2006). Dietary intake of dioxins and dioxin-like PCBs, due to the consumption of dairy products, fish/seafood and meat from Ismailia city, Egypt. Science of the Total Environment, 370(1): 1-8. https://doi.org/10.1016/j.scitotenv.2006.05.012 PMid:16806402

Mohanty M, Pattnaik MM, Mishra AK, and Patra HK (2011). Chromium bioaccumulation in rice grown in contaminated soil and irrigated mine wastewater: A case study at South

Kaliapani chromite mine area, Orissa, India. International Journal of Phytoremediation, 13(5): 397-409. https://doi.org/10.1080/15226511003753979 PMid:21598771

Pehlivan E, Özkan AM, Dinç S, and Parlayici Ş (2009). Adsorption of Cu2+ and Pb2+ ion on dolomite powder. Journal of Hazardous Materials, 167(1-3): 1044-1049. https://doi.org/10.1016/j.jhazmat.2009.01.096 PMid:19237240

Qu CS, Ma ZW, Yang J, Liu Y, Bi J, and Huang L (2012). Human exposure pathways of heavy metals in a lead-zinc mining area, Jiangsu Province, China. PloS One, 7(11): e46793. https://doi.org/10.1371/journal.pone.0046793 PMid:23152752 PMCid:PMC3496726

Reith F, Campbell SG, Ball AS, Pring A, and Southam G (2014). Platinum in earth surface environments. Earth-Science Reviews, 131: 1-21. https://doi.org/10.1016/j.earscirev.2014.01.003

Satpathy D, Reddy MV, and Dhal SP (2014). Risk assessment of heavy metals contamination in paddy soil, plants, and grains (Oryza sativa L.) at the East Coast of India. BioMed Research International, 2014: Article ID 545473. https://doi.org/10.1155/2014/545473 PMid:24995308 PMCid:PMC4065656

Vatansever R, Ozyigit II, and Filiz E (2017). Essential and beneficial trace elements in plants, and their transport in roots: A review. Applied Biochemistry and Biotechnology, 181(1): 464-482. https://doi.org/10.1007/s12010-016-2224-3 PMid:27687587

Wen-Juan J, Che L, Zhou GY, Yang LN, and Hu MY (2016). The bioconcentration ability of heavy metal research for 50 kinds of rice under the same test conditions. Environmental Monitoring and Assessment, 188(12): 1-11. https://doi.org/10.1007/s10661-016-5660-1 PMid:27853967 PMCid:PMC5112290

Zeng F, Mao Y, Cheng W, Wu F, and Zhang G (2008). Genotypic and environmental variation in chromium, cadmium and lead concentrations in rice. Environmental Pollution, 153(2): 309-314. https://doi.org/10.1016/j.envpol.2007.08.022 PMid:17905495

Zhao K, Fu W, Ye Z, and Zhang C (2015). Contamination and spatial variation of heavy metals in the soil-rice system in Nanxun County, Southeastern China. International Journal of Environmental Research and Public Health, 12(2): 1577-1594. https://doi.org/10.3390/ijerph120201577 PMid:25635917 PMCid:PMC4344681

Zhuang P, McBride MB, Xia H, Li N, and Li Z (2009). Health risk from heavy metals via consumption of food crops in the vicinity of Dabaoshan mine, South China. Science of the Total Environment, 407(5): 1551-1561. https://doi.org/10.1016/j.scitotenv.2008.10.061 PMid:19068266